Your home was built under the Pennsylvania Uniform Construction Code and the rough plumbing plans designes approved and inspected under the PA Code enofrced at that time...Likley the plumbing provisions of the 2003 International Residential Code..

This means what you have has been already inspected, approved and allowed based on Code in effect at that time.

Provided that the sewage ejector will not be a "pneumatic" type (which requires it's own independent vent through the roof with no other vents attached), the single 2" vent from the ejector will be adequate to vent the entire bathroom group as designed.

Thank you for your response. Still not clear on the venting questions, though.

When you say that the 2" can vent the entire bathroom, does that mean that I can wet vent the tub and the sink to the pit and the 2" pit vent will suffice? If not, then I understand from your response that I can run separate vents from the tub and sink and then tie them to the pit vent stack as long at the sewage ejector is not pneumatic.

I guess my questions really come down to these two. Based on the sizing of the existing pipes:

Can I wet vent the tub?
Can I wet vent the sink?

I know this was inspected and approved when built, but I don't understand which design it was approved for. (wet venting, or venting as a 'tie into the pit' vent).

Thank you!